This invention relates generally to a method for preparing noncarbon Group IV main group element compounds that contain two reactive sites. More specifically, the method involves cleavage of a cyclic noncarbon Group IV main group element-nitrogen bond with a reactive halide moiety to yield reactive halo and amide functional groups in the same molecule.
The pursuit of a synthetic pathway for incorporating free radical curable functionality onto the siloxane backbone has been long and difficult. For example, it is noted that organosilicon compounds that contain silicon-bonded acylamino-substituted hydrocarbon radicals are known and have been described in publications such as U.S. Pat. No. 4,608,270 to Varaprath, which is herein incorporated by reference. As noted in Varaprath U.S. Pat. No. 4,608,270 and as taught in U.S. Pat. No. 2,929,829 to Morehouse, Japan 51/108022 to Furuya et al., Japan 56/74113 to Takamizawa, and West German DE 2365272 to Koetzsch et al., acylaminoorganopolysiloxanes can be synthesized by reacting aminosiloxanes with the corresponding acid chloride in the presence of a tertiary amine such as triethylamine. Such a synthesis has several disadvantages. First, the removal of the voluminous precipitate of triethylamine hydrochloride by filtration is tedious. Second, even when an excess of amine is used, a small amount of HCl is liberated that is detrimental to the stability of the polymer, especially when the acid chloride has other reactive vinyl functionality such as where the acid chloride is methacrylyl chloride.
An alternative method for the preparation for the acylaminoorganopolysiloxanes involves the reaction of aminosiloxanes and silanes with an acid anhydride or ester at elevated temperature. This is taught in U.S. Pat. No. 4,507,455 to Tangney and Ziemelis, assigned to the assignee of the present invention. Unfortunately at the elevated temperatures of the reaction, acrylamide derivatives undergo Michael addition and amidation of the acrylic double bond resulting in unwanted byproducts and crosslinkage of the desired product which ultimately causes the polymer to gel.
As taught in the above-mentioned U.S. Pat. No. 4,608,270 to Varaprath, these problems can be overcome by reacting the aminosilanes and siloxanes with acid chlorides in the presence of aqueous sodium hydroxide. The HCl that is produced on addition of acyl chloride is neutralized by hydroxide in the aqueous phase. However, a problem arises from the fact that this reaction is carried out in a two-phase system in which the aminosiloxane is dissolved in an organic solvent that is immiscible with water. Because the amide function is generally highly polar and hydrophilic, it has a tendency to absorb moisture. Incorporation of these units into the siloxane backbone increases water miscibility causing the polymers to emulsify easily thus making phase separation difficult.
To some extent, this problem can be overcome by using chlorinated solvents such as methylene chloride or chloroform but, unfortunately, such solvents are toxic. Moreover, when larger amounts of amide functionality or a more resinous structure or both are used, it is almost impossible to prepare such compounds using a two-phase system even when chlorinated solvents are used.
Accordingly, a need remains for an improved method for preparing organosilicon amide compounds that avoids the phase separation and solvent toxicity problems previously encountered. A need remains for an expanded method that permits use of silane starting materials having hydrolytically unstable groups such as Si--O--CH.sub.3. A need remains for an improved method of preparing organosilicon amide compounds that minimizes the production of by-products that must be phase separated, filtered, and/or washed from the product. A need exists to avoid amine and acrylylamide functionality in the starting materials for preparing siloxane polymers and in the starting siloxane polymer itself. Instead the monomeric acrylylamide functionality should be coupled to the silicon polymer as a concluding step. All of these problems and attendant needs strongly suggest that there is still a need for an easy synthetic pathway to incorporate free radical curable functionalities onto the silioxane backbone.
A method for making nitrogen derivatives of a variety of elements is known: EQU Y.sub.3 MNRR'+R"X.fwdarw.Y.sub.3 MX+R"NRR'
where Y is alkyl, aryl, or a halide; M is silicon, germanium, or tin; NRR' is --NRR' (where R and R' are organic radicals), --NCO, NHSi, imidazole, --N.dbd.S.dbd.N--, --N.dbd.CPh.sub.2, --N.sub.3, --NSO, --N.dbd.PR.sub.3, --NSO.sub.2 R, --NPhCSMe, or --NRBEt.sub.2 ; and R"X is acyl halide, alkyl halide, phosgene, PhSO.sub.2 Cl, SO.sub.2 Cl.sub.2, SOCl.sub.2, S.sub.2 Cl.sub.2, ClSO.sub.2 NCO, RN.dbd.SF.sub.2, RN.dbd.SCl.sub.2, R.sub.2 NSCl, ClSO.sub.2 NCO, PCl.sub.3, OPCl.sub.3, PhPOCl.sub.2, (Cl.sub.3 P.dbd.N).sub.2 SO.sub.2, BCl.sub.3, PhBCl.sub.2, R.sub.2 BCl, AlCl.sub.3, FeCl.sub.3, BeCl.sub.2, SbCl.sub.5, PhN.dbd.CCl.sub.2,NOCl, PR.sub.2 F.sub.3, R.sub.2 AsCl, Me.sub.2 NSOCl, S.sub.3 N.sub.2 Cl.sub.2, CF.sub.3 SF.sub.3, (ClSO.sub.2).sub.2 NH, Mn(CO).sub.5 Br, Mo(C.sub.5 H.sub.5)(CO).sub.3 Cl, W(C.sub.5 H.sub.5)(CO).sub.3 Cl, or Ph.sub.2 PCl. This general reaction has been used by German inorganic chemists such as H. Roesky and B. Kuhtz, Chem. Ber. (107) 1 (1974), R. Mews and O. Glemser, Inorg. Chem. (11) 2521 (1972), I. Ruppert, V. Bastian, and R. Appel, Chem. Ber. (108) 2329 (1975), U. Wannagat, Angew. Chem. (77) 626 (1965) and British inorganic chemists such as E. W. Abel and I. D. Towle J. Organomet. Chem. (122)253 (1976) and D. Armitage and A. Sinden J. Inorg. Nucl. Chem. (36) 993 (1974) to make nitrogen derivatives of the elements Be, B, Al, C, Si, Ge, Sn, Ti, P, As, Sb, Nb, Ta, S, Mo, W, Mn, Fe, Rh from complex element halides and usually the trimethylsilyl derivative of the nitrogen compound. The driving force of the reaction is the easy removal of byproduct halosilane, the preferential pairing of the electropositive Si with electronegative halide, and the delocalization of the nitrogen lone pair in most reaction products.
This reaction proceeds rapidly in high yields at low temperatures. For example, ##STR1## K. Farmery, M. Kilner and C. Midcalf, J. Chem. Soc. (A) 2279 (1970); EQU Si(NMe.sub.2).sub.4 +4PhCOCl--reflux, no solvent.fwdarw.4PhCONMe.sub.2 +SiCl.sub.4,
H. H. Anderson, J. Amer. Chem Soc. (74) 1421 (1962); EQU Me.sub.2 NSiMe.sub.3 +NOCl (excess)--25.degree. C., exothermic, no solvent, 73% yield.fwdarw.Me.sub.2 NNO+Me.sub.3 SiCl
J. E. Byrne and C. R. Russ, J. Orqanometal. Chem. (22) 357 (1970); and ##STR2## J. R. Bowser, P. J. Williams, and K. Kurz, J. Org. Chem. (48) 4111 (1983).
However, the general reaction does not produce interesting organosilicon compounds and thus has been of little interest to the organosilicon chemist. There have been no reports of this type of reaction being run with acrylyl chloride or methacrylyl chloride nor has there ever been mention of using a heterocyclic form of the noncarbon Group IV main group element-nitrogen linkage as part of this reaction. Certainly it has never been suggested that this type of reaction could serve as a synthetic pathway to incorporate free radical curable functionalities onto a silioxane backbone.